[Tutor] concat vs join - followup

[Danny Yoo]

> > I started this experiment because I have been telling people on the
> > Tutor mailing list to use join, and I wondered how much it really
> > mattered. Does it make enough of a difference to bring it up to
> > beginners? I'm not sure.
>
> Its easy to get carried away with premature optimisation. I did the same
> in my tutor by mentioning that a deferred import is slightly faster, now
> I see lots of folks deferring imports in inappropriate cases and wish
> I'd kept my advise to myself because the performamce win is tiny and the
> readability loss significant!

Hi Alan,

There's an awesome quote by the folks who wrote SICP that goes:

    ... we want to establish the idea that a computer language is not just
    a way of getting a computer to perform operations but rather that it
    is a novel formal medium for expressing ideas about methodology.
    Programs must be written for people to read, and only incidentally for
    machines to execute.

I think we should stress on readability for beginners.  Readability is
often what brings people to Python, and not necessarily its performance.